radiance
Well-known member
Well, well well, what have we here. Ten meters Frank. You must be in meassuring heaven.
I want a new Multi Meter
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clintrubber
Well-known member
Nothing wrong with a second, third, fourth, fifth... opinion :grin:
What's the stuff upper right in the picture ? Some plugins with tube-sockets ?
nrgrecording
Well-known member
Hi Clintrubber.
Thats the "Bias Master" from ruby tubes. Nothing special.
It's to adjust the correct bias point in tube amps with 6L6GC, 6550, EL34, KT66, KT88...
I'd seen some infos somewhere how you can build one yourselfes. It was pretty easy. I bought a used one for some bucks.
I've got several amps and readjusting the bias point every 6 month because of the drift of the working point (tube) isn't a bad idea i think. :wink:
With the tubemaster you put the adapter between the sockets and the tubes. Then you can measure the bias of every tube by switching between the sockets. If the amp has the ability to set the bias point at every tube you don't have to buy expensive matched tubes.
Here is a bigger picture... Looks a bit like homebrew stuff :green:
Thats the "Bias Master" from ruby tubes. Nothing special.
It's to adjust the correct bias point in tube amps with 6L6GC, 6550, EL34, KT66, KT88...
I'd seen some infos somewhere how you can build one yourselfes. It was pretty easy. I bought a used one for some bucks.
I've got several amps and readjusting the bias point every 6 month because of the drift of the working point (tube) isn't a bad idea i think. :wink:
With the tubemaster you put the adapter between the sockets and the tubes. Then you can measure the bias of every tube by switching between the sockets. If the amp has the ability to set the bias point at every tube you don't have to buy expensive matched tubes.
Here is a bigger picture... Looks a bit like homebrew stuff :green:
SonsOfThunder
Well-known member
[quote author="PRR"]Maybe ones that say "RMS" also cover the audio band. I would not bet on it without testing.[/quote] Nope! Some Fluke 7x series are "True RMS" but don't go above about 400Hz or so as you say.
HTH!
Charlie
Quick and dirty: Use a signal generator and sweep it with a set amount of output!
Nope, maybe "Nirvana"...this is measuring "Heaven"!
HTH!
Charlie
SSLtech
Well-known member
Scenaria... you got a second one????
Sheeeesh!!!!
Sheeeesh!!!!
radiance
Well-known member
He probably cloned it. No, wait, they are both clones right?
> Quick and dirty: Use a signal generator and sweep it
Yes.... except I am noticing that a LOT of folk here don't own a signal generator.
That, to me, is inconceivable. You need both inputs AND outputs to get anywhere.
And while a PC/Mac tone program or a test-CD can be used in a pinch, that's not really my way to live.
I have about four signal generators here. A much-modified Heathkit that goes down to a fraction of a Hz with a calibrated attenuator, the Circuit Specialties 2001 which is more stable but uncalibrated and somewhat dirty (being a function generator), and a couple of The Beasts (H-P 200 series). On top of pinkish-noise, PC-based, test-CD, and other sources. I know I own a dozen meters but I only have three handy.
I think a signal generator is essential when you get past the "does it work?" stage (whether it turns out to work or not). If it works, you need to run some sweeps in frequency and level, know if it is flat and can go loud. If it don't work, maybe a meter will show you a problem, and sometimes you need to send a steady reliable signal in and see where it is getting lost.
I've accumulated sig-gens for decades. I was a bit flustered when I went to look for new ones. There is a limited sub-$99 handheld, some neat tricks but discrete frequencies and levels. That "cheap" CS 2001 is close to $200 now. Heath is dead and we never could afford H-P, especially now that they is Agulent. It starts to look like getting a decent multimeter and a sig-gen New is way over $100, and possibly over $250, $2,000 if you have the bucks. Hell, half the stuff I fix isn't worth $250.
But some of the eBay listings are interesting. Since I have the basics, I get lost in oddballs. I didn't know Motorola made a line of early transistor test gear. Someone had some oh-so-1963 rounded-case Motorolas: sig-gen and "VT"VM and RF-gen, the whole set sold for like $50 a box. Good VTVMs are $10, and that plus a $10 DVM is enough metering for me. (Good VTVMs have dB marks on the volts scales.) Good sig-gens turn up less often, but the going rate for a lightly-dented H-P 200 is $50, and all they ever need is cleaning and lubrication.
Yes.... except I am noticing that a LOT of folk here don't own a signal generator.
That, to me, is inconceivable. You need both inputs AND outputs to get anywhere.
And while a PC/Mac tone program or a test-CD can be used in a pinch, that's not really my way to live.
I have about four signal generators here. A much-modified Heathkit that goes down to a fraction of a Hz with a calibrated attenuator, the Circuit Specialties 2001 which is more stable but uncalibrated and somewhat dirty (being a function generator), and a couple of The Beasts (H-P 200 series). On top of pinkish-noise, PC-based, test-CD, and other sources. I know I own a dozen meters but I only have three handy.
I think a signal generator is essential when you get past the "does it work?" stage (whether it turns out to work or not). If it works, you need to run some sweeps in frequency and level, know if it is flat and can go loud. If it don't work, maybe a meter will show you a problem, and sometimes you need to send a steady reliable signal in and see where it is getting lost.
I've accumulated sig-gens for decades. I was a bit flustered when I went to look for new ones. There is a limited sub-$99 handheld, some neat tricks but discrete frequencies and levels. That "cheap" CS 2001 is close to $200 now. Heath is dead and we never could afford H-P, especially now that they is Agulent. It starts to look like getting a decent multimeter and a sig-gen New is way over $100, and possibly over $250, $2,000 if you have the bucks. Hell, half the stuff I fix isn't worth $250.
But some of the eBay listings are interesting. Since I have the basics, I get lost in oddballs. I didn't know Motorola made a line of early transistor test gear. Someone had some oh-so-1963 rounded-case Motorolas: sig-gen and "VT"VM and RF-gen, the whole set sold for like $50 a box. Good VTVMs are $10, and that plus a $10 DVM is enough metering for me. (Good VTVMs have dB marks on the volts scales.) Good sig-gens turn up less often, but the going rate for a lightly-dented H-P 200 is $50, and all they ever need is cleaning and lubrication.
tmbg
Well-known member
I broke down and bought a "cheap" B&K function gen, that does 0-4MHz, lin/log sweeps, DC offset, external triggering, frequency counter, etc...
it was friggin $350.
But yeah, seriously, you MUST have a function generator, a decent meter, and a halfway decent scope. I wish my halfway decent scopes were more decent My 50MHz philips cannot show a sharp line, and I don't think it's the CRT's fault, and my 100MHz tek digital just has some sort of weird problem that I have no idea how to fix
it was friggin $350.
But yeah, seriously, you MUST have a function generator, a decent meter, and a halfway decent scope. I wish my halfway decent scopes were more decent
My 50MHz philips cannot show a sharp line, and I don't think it's the CRT's fault, and my 100MHz tek digital just has some sort of weird problem that I have no idea how to fix This is a way-cool very-vintage VTVM.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4678&item=3861296334&rd=1
I know it is old because "0dB = 6 milliwatts in 500 ohms", the pre-VU standard. So this was designed before 1937 or so. The art-deco styling also says "vintage".
It appears to be a true VTVM, not a passive meter: note the "zero adjust" to trim out tube unbalance. (It can't be a 12AU7; wonder what they used?)
Also, it has separate AC/Ohms and DC inputs. many later meters have this switch on the probe, which gets lost over the years. This just needs pin-leads.
The same vendor has an RCA cheap-clone of the HP-200 sine generator (plus square). And a rack-scope that would look cool in a rack, but isn't very fast and takes LOTs of tubes. I've used worse, but I mainly think it is good for keeping stoned clients amused and out of trouble. Assuming you can keep it working. Very fixable, but potentially a lot of fixing.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4678&item=3861296334&rd=1
I know it is old because "0dB = 6 milliwatts in 500 ohms", the pre-VU standard. So this was designed before 1937 or so. The art-deco styling also says "vintage".
It appears to be a true VTVM, not a passive meter: note the "zero adjust" to trim out tube unbalance. (It can't be a 12AU7; wonder what they used?)
Also, it has separate AC/Ohms and DC inputs. many later meters have this switch on the probe, which gets lost over the years. This just needs pin-leads.
The same vendor has an RCA cheap-clone of the HP-200 sine generator (plus square). And a rack-scope that would look cool in a rack, but isn't very fast and takes LOTs of tubes. I've used worse, but I mainly think it is good for keeping stoned clients amused and out of trouble. Assuming you can keep it working. Very fixable, but potentially a lot of fixing.
nrgrecording
Well-known member
I also bought this multi measurement station and it is ok for me. It is at least the heaviest multimeter i have. :green:
An AP 2700 is a bit 'uncheap'. :? Hey... but I can connect this box with my computer also :roll: (terrible software) :wink:
Power Supply 15V, 5V and 0-30V with LCD Display
GND free or grounded, current and voltage adjustable
shows voltage or current in display
Multimeter(Metex type) TRUE RMS Multimeter 3 3/4 digit LCD double display with bar graph and back-lighting. Automatic range selection with Min./Max. save, Data-Hold and REL function. DC V: 0.1 mV ... 1000 V at ± 0.3% + 1 digit AC V (TRUE-RMS): 0.1 mV ... 750 V at ± 1% + 3 digit DC A: 10 µA ... 20 A at ± 0.8% + 1 digit AC A (TRUE-RMS): 10 µA ... 20A at ± 2.5% + 3 digit R: 1 W ... 40 MW at ± 0.5% +1 digit L: 10 µH ... 400 mH at ± 3% + 10 digits C: 1 pF ... 400 µF at ± 3% +5 digits In addition, acoustic continuity tester, plus diode and logistic test function. Built-in RS 232 interface.
Function Generator Wave forms: sinusoid, rectangular, triangle, ramps, pulses, TTL · frequency range: 1 Hz - 10 MHz (7 ranges) · Output impedance: 50W ±10%, 600 W ± 10% · Amplitude: 2 Vpp-20 Vpp · Attenuator: -20 dB
Universal Counter LED Frequency meter: 8 digit LED display with switched peak times of 0.1, 1 and 10 seconds. Measurement range 5 Hz to 1.3 GHz. Inputs A/B: 5 - 100 MHz · Sensitivity 20 mV · Input resistance 1 MW/100 pF · Representation of functions A + B, A - B and A/B · Switchover option to period measurement. Input C: 100 MHz to 1.3 GHz · Sensitivity 20 mV · Input impedance 50W
An AP 2700 is a bit 'uncheap'. :? Hey... but I can connect this box with my computer also :roll: (terrible software) :wink:
Power Supply 15V, 5V and 0-30V with LCD Display
GND free or grounded, current and voltage adjustable
shows voltage or current in display
Multimeter(Metex type) TRUE RMS Multimeter 3 3/4 digit LCD double display with bar graph and back-lighting. Automatic range selection with Min./Max. save, Data-Hold and REL function. DC V: 0.1 mV ... 1000 V at ± 0.3% + 1 digit AC V (TRUE-RMS): 0.1 mV ... 750 V at ± 1% + 3 digit DC A: 10 µA ... 20 A at ± 0.8% + 1 digit AC A (TRUE-RMS): 10 µA ... 20A at ± 2.5% + 3 digit R: 1 W ... 40 MW at ± 0.5% +1 digit L: 10 µH ... 400 mH at ± 3% + 10 digits C: 1 pF ... 400 µF at ± 3% +5 digits In addition, acoustic continuity tester, plus diode and logistic test function. Built-in RS 232 interface.
Function Generator Wave forms: sinusoid, rectangular, triangle, ramps, pulses, TTL · frequency range: 1 Hz - 10 MHz (7 ranges) · Output impedance: 50W ±10%, 600 W ± 10% · Amplitude: 2 Vpp-20 Vpp · Attenuator: -20 dB
Universal Counter LED Frequency meter: 8 digit LED display with switched peak times of 0.1, 1 and 10 seconds. Measurement range 5 Hz to 1.3 GHz. Inputs A/B: 5 - 100 MHz · Sensitivity 20 mV · Input resistance 1 MW/100 pF · Representation of functions A + B, A - B and A/B · Switchover option to period measurement. Input C: 100 MHz to 1.3 GHz · Sensitivity 20 mV · Input impedance 50W
NewYorkDave
Well-known member
Luckily, you can build a low-distortion sine generator for cheap with some common parts. Here's a fixed 400Hz model I built for our TV studio:
Schematic
You can make the frequency variable by using a dual-ganged pot for R1/R2, and making C1/C2 switchable for different ranges. It's a Wien bridge circuit, so calculate the frequencies using the usual R-C formulas. Use a larger output coupling cap if you want to use this circuit at frequencies lower than 400Hz.
You need a slightly more sophisticated version if you can't tolerate a distortion rise at very low audio frequencies. Go to http://www.linear.com and search for AN43. This is an application note by Jim Williams about bridge circuits; a discussion of Wien bridge oscillators of very low distortion begins on page 29.
If you need very high output voltage or fairly high output power, you're better off buying an old tube HP 200-series.
Function generators are handy, but their sinewave outputs are not of low enough distortion for THD measurements. A well-equipped DIY lab will have a function generator AND a low-distortion sine generator.
Schematic
You can make the frequency variable by using a dual-ganged pot for R1/R2, and making C1/C2 switchable for different ranges. It's a Wien bridge circuit, so calculate the frequencies using the usual R-C formulas. Use a larger output coupling cap if you want to use this circuit at frequencies lower than 400Hz.
You need a slightly more sophisticated version if you can't tolerate a distortion rise at very low audio frequencies. Go to http://www.linear.com and search for AN43. This is an application note by Jim Williams about bridge circuits; a discussion of Wien bridge oscillators of very low distortion begins on page 29.
If you need very high output voltage or fairly high output power, you're better off buying an old tube HP 200-series.
Function generators are handy, but their sinewave outputs are not of low enough distortion for THD measurements. A well-equipped DIY lab will have a function generator AND a low-distortion sine generator.
CJ
Well-known member
I agree on the True RMS deal. It;s mostly a marketing buzzword.
Raises the price of the meter, thats about all. Really, the only time you need true rms is for stuff like vfd's (variable frequency drives) where the waveform gets chopped to hell.
Funny thing, we sell a true rms current sensor and a regular current sensor. The true rms is about 30 percent more expensive, but guess what? There both the same circuit! They figured out that it would be cheaper to stock one version instead of two, so they use the same product and give it two names!
I better edit this in a while, the boss would kill me. So if the customer knew, he could get the true rms sensor for 30 percent off!
Non true rms meters are good for measuring transformers, as you want the average of the magnetizing current, not the rms value.
I have a talking voltmeter that I bought at Radio Shack. You push a button on the probe and a voice tells you the voltage. Pretty slick idea but it didn't catch on so they quit making them.
I get to use this 20,000 dollar volt/power meter at work. It just came back from calibration. UPS dropped the darn thing and smashed the heck out of the front panel!
Yokogawa managed to save it.
Raises the price of the meter, thats about all. Really, the only time you need true rms is for stuff like vfd's (variable frequency drives) where the waveform gets chopped to hell.
Funny thing, we sell a true rms current sensor and a regular current sensor. The true rms is about 30 percent more expensive, but guess what? There both the same circuit! They figured out that it would be cheaper to stock one version instead of two, so they use the same product and give it two names!
I better edit this in a while, the boss would kill me. So if the customer knew, he could get the true rms sensor for 30 percent off!
Non true rms meters are good for measuring transformers, as you want the average of the magnetizing current, not the rms value.
I have a talking voltmeter that I bought at Radio Shack. You push a button on the probe and a voice tells you the voltage. Pretty slick idea but it didn't catch on so they quit making them.
I get to use this 20,000 dollar volt/power meter at work. It just came back from calibration. UPS dropped the darn thing and smashed the heck out of the front panel!
Yokogawa managed to save it.
NewYorkDave
Well-known member
That reminds me of a chat I had with an engineer at the 2001 NAB convention. His company sells portable transmitters. These have a high-power setting that is accessed by DIP switches, which supposedly works only on the "export" models. These DIP switches are present but allegedly disabled in the "domestic" models. The engineer confided that there is NO difference between the transmitters, the domestic and export models are one and the same. They just put that stuff in their manual to keep the friendly candy company off their backs. :wink:
clintrubber
Well-known member
As probably brought up here before, it's a common 'trick' for ICs as well.
Just make one version of the actual IC (die/chip) and configure it for variations in functionality (and so different prices) with the bonding.
A common variation is a 'dumb' version and a 'smart' (bus-controlled)version of an IC.
It's not the most fun part of a project though.
We've been working on a chip that has to be made in about three to four versions and a few different kinds of packages - pre-arranging bondpads for all those different bonding schemes has been a nightmare.
Peter
Just make one version of the actual IC (die/chip) and configure it for variations in functionality (and so different prices) with the bonding.
A common variation is a 'dumb' version and a 'smart' (bus-controlled)version of an IC.
It's not the most fun part of a project though.
We've been working on a chip that has to be made in about three to four versions and a few different kinds of packages - pre-arranging bondpads for all those different bonding schemes has been a nightmare.
Peter
SonsOfThunder
Well-known member
[quote author="tmbg"]I broke down and bought a "cheap" B&K function gen[/quote] B&K or B+K Precision? I have a hard time believing that it was really B&K for $350. BK Precision stuff is usually >3% distortion, btw.
HTH!
Have you tried cleaning the time base switch with DeOxit? I have a 100MHz Tek at work that suddenly went wonky and it took a couple of switch cleanings to get it straightened out.my 100MHz tek digital just has some sort of weird problem that I have no idea how to fix
HTH!
SonsOfThunder
Well-known member
[quote author="nrgrecording"]
[/quote]
Wow! Who makes this? Looks like an ultimate DIY tool!
Peace!
Wow! Who makes this? Looks like an ultimate DIY tool!
Peace!
tmbg
Well-known member
[quote author="SonsOfThunder"][quote author="tmbg"]I broke down and bought a "cheap" B&K function gen[/quote] B&K or B+K Precision? I have a hard time believing that it was really B&K for $350. BK Precision stuff is usually >3% distortion, btw.
HTH![/quote]
B+K precision. "cheap".
I can try cleaning the switches... the weird problem that it has is that the signal on channel 1 modulates the channel 2 trace and the on screen text.
Which 100MHz tek do you have? Is it a digital one? Mine's a 2230... I have some questions about it. I wish I could find a manual.
Have you tried cleaning the time base switch with DeOxit? I have a 100MHz Tek at work that suddenly went wonky and it took a couple of switch cleanings to get it straightened out.my 100MHz tek digital just has some sort of weird problem that I have no idea how to fix
HTH![/quote]
B+K precision. "cheap".
I can try cleaning the switches... the weird problem that it has is that the signal on channel 1 modulates the channel 2 trace and the on screen text.
Which 100MHz tek do you have? Is it a digital one? Mine's a 2230... I have some questions about it. I wish I could find a manual.
nrgrecording
Well-known member
[quote author="SonsOfThunder"][quote author="nrgrecording"]
Wow! Who makes this? Looks like an ultimate DIY tool!
Peace![/quote]
http://www.metex.co.kr/index_product_e.html
available from conrad.com and other electronic supplier.
If it is available in germany maybe it is available in atlanta, too?
It's made in japan.
Name is: "METEX MS-9150 Multi Measurement Station"
Wow! Who makes this? Looks like an ultimate DIY tool!
Peace![/quote]
http://www.metex.co.kr/index_product_e.html
available from conrad.com and other electronic supplier.
If it is available in germany maybe it is available in atlanta, too?
It's made in japan.
Name is: "METEX MS-9150 Multi Measurement Station"
CJ
Well-known member
Sometimes cheaper is better. This $19.95 Soar, which has been discontinued much to my chagrin is the BOM.
It runs on AA's which last a heck of a lot longer than expensive 9 volts, it's easy as heck to change the battery, no screws to undo, (btw, these idiot calibration labs put stickers over the screws that say if this seal is broken, blah blah blah, well guess what, technically then, every time you change the battery, it's no loger certified!) it takes up less table space, the controls are very logical, and it has lasted 14 years of getting dropped, nuked by hv, ma into the ohms, etc.
It's held together with shipping tape.
I probably trouble shot 10,000 circuit boards with it, and the guy using it now has proabaly fixed another 10,000.
I have a cheap signal generator that I love also. You can find the self resonance of a transformer by watching the output voltage. It starts to sag when the transformer starts gobbling up high frequency sine waves. Just sweep until the voltage drops the lowest and you have found the area of first resonance.
It runs on AA's which last a heck of a lot longer than expensive 9 volts, it's easy as heck to change the battery, no screws to undo, (btw, these idiot calibration labs put stickers over the screws that say if this seal is broken, blah blah blah, well guess what, technically then, every time you change the battery, it's no loger certified!) it takes up less table space, the controls are very logical, and it has lasted 14 years of getting dropped, nuked by hv, ma into the ohms, etc.
It's held together with shipping tape.
I probably trouble shot 10,000 circuit boards with it, and the guy using it now has proabaly fixed another 10,000.
I have a cheap signal generator that I love also. You can find the self resonance of a transformer by watching the output voltage. It starts to sag when the transformer starts gobbling up high frequency sine waves. Just sweep until the voltage drops the lowest and you have found the area of first resonance.
